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Electrochemical Approach (electrochemical + approach)

Distribution by Scientific Domains
Chemistry75%
Polymers and Materials Science25%

Selected Abstracts

Electrochemical Approach to the Radical Anion Formation from 2,-Hydroxy Chalcone Derivatives

ELECTROANALYSIS, Issue 5 2006
P. Quintana-Espinoza
Abstract Three 2,-hydroxy chalcone derivatives were electrochemically reduced to the radical anion by a reversible one-electron transfer followed by a chemical dimerization reaction. Under suitable conditions of the medium, the one-electron reduction produces very well resolved cyclic voltammograms due to the formation of the radical anion. By using appropriately the wide versatility of the cyclic voltammetric technique, was possible to study the generation of the radical anion and its stability. [source]

Comparison of Different Strategies on DNA Chip Fabrication and DNA-Sensing: Optical and Electrochemical Approaches

ELECTROANALYSIS, Issue 22 2005
Sabine Szunerits
Abstract New strategies for the construction of DNA chips and the detection of DNA hybridization will be discussed in this review. The focus will be on the use of polypyrrole as a linker between a substrate and oligonucleotide probes. The modification step is based on the electrochemical copolymerization of pyrrole and oligonucleotides bearing a pyrrole group on its 5, end. This strategy was employed for the immobilization of oligonucleotides on millimeter-sized electrodes, microelectrode arrays, as well as for the local structuring of homogeneous gold surfaces. Our approaches for the localized patterning of gold surfaces will be also discussed. Localized immobilization was achieved by using an electrospotting technique, where a micropipette served as an electrochemical cell where spot sizes with 800,,m diameters were fabricated. The use of a microcell using a Teflon covered metal needle with a cavity of 100,,m resulted in immobilized probe spots of 300,,m. Scanning electrochemical microscopy (SECM) was also used, and surface modifications of 100,,m were obtained depending on the experimental conditions. Different detection methods were employed for the reading of the hybridization event: fluorescence imaging, surface plasmon resonance imaging (SPRI), photocurrent measurements, and voltamperometric measurements using intercalators. Their advantages concerning the various immobilization strategies will also be discussed. [source]

One-Step Ionic-Liquid-Assisted Electrochemical Synthesis of Ionic-Liquid-Functionalized Graphene Sheets Directly from Graphite,

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2008
Na Liu
Abstract Graphite, inexpensive and available in large quantities, unfortunately does not readily exfoliate to yield individual graphene sheets. Here a mild, one-step electrochemical approach for the preparation of ionic-liquid-functionalized graphite sheets with the assistance of an ionic liquid and water is presented. These ionic-liquid-treated graphite sheets can be exfoliated into functionalized graphene nanosheets that can not only be individuated and homogeneously distributed into polar aprotic solvents, but also need not be further deoxidized. Different types of ionic liquids and different ratios of the ionic liquid to water can influence the properties of the graphene nanosheets. Graphene nanosheet/polystyrene composites synthesized by a liquid-phase blend route exhibit a percolation threshold of 0.1 vol % for room temperature electrical conductivity, and, at only 4.19 vol %, this composite has a conductivity of 13.84,S m,1, which is 3,15 times that of polystyrene composites filled with single-walled carbon nanotubes. [source]

Creating In-Plane Metallic-Nanowire Arrays by Corner-Mediated Electrodeposition

ADVANCED MATERIALS, Issue 35 2009
Bo Zhang
A novel template-assisted electrochemical approach to fabricate in-plane arrays of copper nanowires with tunable width varying from 25,nm to more than 200,nm, which is realized by successive nucleation of copper at the concave corner of the polymer template and the substrate, is reported. We demonstrate that this method can be applied for fabricating complicated structures. [source]

An ESR and electrochemical approach to the unusual reactivity of ferrocenoylsilanes with organometallic compounds

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 12 2004
A. Alberti
Abstract ESR studies carried out during the reaction of ferrocenoylsilanes with Grignard reagents at low temperature led to the detection of the radical anions of the former compounds. Cyclic voltammetric experiments indicate that the observed radical anions are likely to originate through an inner-sphere electron transfer process. Different radical species were observed upon annealing, originating from destruction of the ferrocenyl moiety. Paramagnetic species were also detected on reacting ferrocenoylsilanes with LiAlH4. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Direct Electrochemical Sensing and Detection of Natural Antioxidants and Antioxidant Capacity in Vitro Systems

ELECTROANALYSIS, Issue 22 2007
Antonio, Javier Blasco
Abstract This review highlights the role of electrochemical approaches in the sensing of antioxidants and their antioxidant capacity with especial attention to the analytical possibilities of electrochemistry in the direct evaluation of antioxidant capacity exhibited by food and biological samples due to the termed dietary, natural or biological antioxidants (mainly polyphenols, and vitamins C and E). The analytical potency of the electrochemistry is comprehensively stated and the selected results found in the literature are summarized and discussed critically. The main electrochemical approaches used have been cyclic voltammetry (CV) and flow injection analysis with amperometric detection (FIA-ED). In addition, miniaturization is going to break new frontiers in the evaluation of antioxidant activity. [source]

L -Cysteine Voltammetry at a Carbon Paste Electrode Bulk-Modified with Ferrocenedicarboxylic Acid

ELECTROANALYSIS, Issue 17 2007
Jahan-Bakhsh Raoof
Abstract The electrochemical behavior of L -cysteine studied at the surface of ferrocenedicarboxylic acid modified carbon paste electrode (FDCMCPE) in aqueous media using cyclic voltammetry, differential pulse voltammetry and double potential step chronoamperometry. It has been found that under optimum condition (pH,8.00) in cyclic voltammetry, the oxidation of L -cysteine occurs at a potential about 200,mV less positive than that of an unmodified carbon paste electrode. The kinetic parameters such as electron transfer coefficient, ,, and catalytic reaction rate constant, kh were also determined using electrochemical approaches. The electrocatalytic oxidation peak current of L -cysteine showed a linear dependent on the L -cysteine concentration and linear analytical curves were obtained in the ranges of 3.0×10,5 M,2.2×10,3 M and 1.5×10,5 M,3.2×10,3 M of L -cysteine concentration with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods respectively. The detection limits (3,) were determined as 2.6×10,5 M and 1.4×10,6 M by CV and DPV methods. [source]

Electrocatalysis and Voltammetric Determination of Dopamine at a Calix[4]arene Crown-4 Ether Modified Glassy Carbon Electrode

ELECTROANALYSIS, Issue 4 2007
Guo-Song Lai
Abstract A sensitive and selective electrochemical method for the determination of dopamine (DA) was developed using a calix[4]arene crown-4 ether (CACE) film modified glassy carbon electrode (GCE). The modified electrode exhibited good electrocatalytic activity for electrochemical oxidation of DA in the pH,6.00 Britton,Robinson buffer solution, and ascorbic acid (AA) did not interfere with it. The diffusion coefficient (D=2.7×10,5,cm2 s,1), and the kinetic parameter such as the electron transfer coefficient (,=0.54) of DA at the surface of CACE were determined using electrochemical approaches. The catalytic oxidation peak currents showed a linear dependence on the DA concentration and a linear analytical curve was obtained in the range of 2.0×10,5,1.0×10,3,M of DA with a correlation coefficient of 0.9990. The detection limit (S/N=3) was estimated to be 3.4×10,6,M. This method was also examined for the determination of DA in an injection sample. In addition, effects of possible interferences were investigated. The present work shows the potential of the proposed method for the fabrication of a modified electrode, as it can be effectively used for voltammetric detection of DA. [source]